Fabrication help/question

I have absolutely zero fabrication skills/tools, but would like to mount one of these:

https://smile.amazon.com/dp/B07F84VV...v_ov_lig_dp_it

in my 1964 Skylark Convertible. I have gone through several options (some of them on here), like replacing the cigar lighter or the Accessory switch, but would rather hide it in place of the ash tray. Obviously the tray itself would have to come out, but that's easy. I would need a small bracket fabricated that would attach (via rivets?) to bottom of the dash behind the ashtray lid. Would have to paint it black to match the dash.

I can template in cardboard first, but what's the best way to make it?

Any thoughts or suggestions??
John

sheet metal, hole saw, tin snips, pop rivets?